Electrochemical properties of plasticized PVA-based electrolyte inserted with alumina nanoparticles for EDLC application with enhanced dielectric constant

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In the current study, the role of alumina nanoparticles was examined in the electrochemical and device performance of PVA-based electrolytes. The NaSCN was used as a cation provider for the host electrolyte, and the glycerol plasticizers were used to enhance conductivity and flexibility. The ratio of salt and plasticizer was fixed, while nanoparticles were varied. The results of impedance AC conductivity confirm that 3 wt% of alumina insertion results in high DC conductivity, which is sufficient for electrochemical device application. Electrode polarization region and plateau area are clearly distinguished in AC spectra. The study of the Dielectric constant reveals that charge storage is maximum at 3 wt% of alumina. The dielectric constant values are about twice the dielectric loss value, which is the topic of immense scientific discussion. The contribution of ion fraction was found to be 0.94, which is excellent compared to the negligible contribution of electrons, which is about 0.05. Electrochemical stability is an additional crucial factor and was found to be 2.47 V. To identify any Redox or non-Redox phenomena occurring in the electrical double-layer capacitor (EDLC) cyclic voltammetry (CV) as the simplest analysis method has been carried out on the sample having the highest DC value. A leaf-like form of the CV plot was noticed at high scan rates, while a rectangular shape was identified at low scan rates. The charge-discharge shape is almost close to the ideal triangular pattern. The discharge part was used to calculate critical EDLC device parameters such as ESR, efficiency, specific capacitance power density, and energy density over 2000 cycles. Low ESR (below 60 Ω) and stable efficiency (almost 100 %) of the device results in high capacitance (≈87 F/g), power density (2978 Wh/kg), and energy density (12.86 W kg−1). The results established that nan-fillers alongside plasticizer is crucial to deliver EDLC devices with improved performances.